When you get your Christmas presents wrapped and the kids off to bed, sometimes there's a great football game on TV. If you get beyond that, it's time to read a good book. You may want to consider astronomer Carl Sagan 's The Demon Haunted World: Science as a Candle in the Dark . Amazon.com has this to say about the book:
Carl Sagan muses on the current state of scientific thought, which offers him marvelous opportunities to entertain us with his own childhood experiences, the newspaper morgues, UFO stories, and the assorted flotsam and jetsam of pseudoscience. Along the way he debunks alien abduction, faith-healing, and channeling; refutes the arguments that science destroys spirituality, and provides a "baloney detection kit" for thinking through political, social, religious, and other issues.
Chapter 12 is the "baloney detection" part and it brought a flood of recognition illuminating the current debate on salt and health. Consider Sagan's tools for testing arguments to uncover fallacy or fraud. They include encouraging substantive debate, dismissing arguments from authority and suggesting a healthy dose of humility and openness to new perspectives. He advises seeking evidence that can rule out hypotheses even while their validity is unproven and extols high quality controlled trials. Insightful and relevant, I hope you agree.
Sagan proceeds to identify common fallacies of logic and rhetoric. See if you recognize any patterns here in the salt and health debate. These include:
Ad hominem - attacking the arguer and not the argument.
Argument from "authority".
Argument from adverse consequences (putting pressure on the decision maker by pointing out dire consequences of an "unfavorable" decision).
Appeal to ignorance (absence of evidence is not evidence of absence).
Special pleading (typically referring to god's will).
Begging the question (assuming an answer in the way the question is phrased).
Observational selection (counting the hits and forgetting the misses).
Statistics of small numbers (such as drawing conclusions from inadequate sample sizes).
Misunderstanding the nature of statistics (President Eisenhower expressing astonishment and alarm on discovering that fully half of all Americans have below average intelligence!)
Inconsistency (e.g. military expenditures based on worst case scenarios but scientific projections on environmental dangers thriftily ignored because they are not "proved").
Non sequitur - "it does not follow" - the logic falls down.
Post hoc, ergo propter hoc - "it happened after so it was caused by" - confusion of cause and effect.
Meaningless question ("what happens when an irresistible force meets an immovable object?).
Excluded middle - considering only the two extremes in a range of possibilities (making the "other side" look worse than it really is).
Short-term v. long-term - a subset of excluded middle ("why pursue fundamental science when we have so huge a budget deficit?").
Slippery slope - a subset of excluded middle - unwarranted extrapolation of the effects (give an inch and they will take a mile).
Confusion of correlation and causation.
Straw man - caricaturing (or stereotyping) a position to make it easier to attack.
Suppressed evidence or half-truths.
Weasel words - for example, use of euphemisms for war such as "police action" to get around limitations on Presidential powers. "An important art of politicians is to find new names for institutions which under old names have become odious to the public"
This is rich; a mother lode.
It would take an all-day read of this blog to offer the myriad examples of these fallacies and rhetorical tricks. Those of us who have spoken to the issue have been subjected to many; and our appeals, for example, for a controlled trial of health outcomes of dietary sodium in preference for valuing "argument from authority," is but the most glaring example.
Thanks to Michael Paine of The Planetary Society Australian Volunteers for the good advice I'm passing along.
